^ Whoa there, your math is off by a bit.
It's good to allow some head room for overclocking and whatnot, so we'll call the i5 110 watts. The GTX 570 has a tdp, or maximum power usage, of 219W, but you could probably hit 260 with a particularly beastly overclock. So that's 370W for those components. Add 40 for your fans, 30 for the RAM, 15 for the HDD, 30 for the mobo, and another 20 for whatever else you might happen to have connected, and you have a conservative rating of 505W with everything heavily overclocked and completely maxed out...a very rare occurance.
Given those numbers, I'd shoot for a good one at around 600W to allow for some upgrading headroom, and also for capacitor aging if you plan on keeping that PSU for a long time. Seasonic's 620W S12II units are particularly good for their comparatively low price.
Granted, if you want to add a second 570 at some point, I'd shoot quite a bit higher...